The invention relates to multiple, opposed, reciprocating piston engines driven by alternating, segmented rack and pinion gears, along the centerline of the cylinder, without the eccentric side force required in a conventional crankshaft or sinusoidal-cam driven shaft. The engine is supercharged with a single sealed spherical rotary valve similar in diameter to the cylinder bore. This engine is very compact and may replace any conventional reciprocating engine presently in use.
The advantages of the invention will be listed and are the result of two major improvements, the first being a constant-torque-arm input of the piston travel to the alternating rack and pinion gears, and the second the use of a large diameter spherical valve which, in one rotation accomplishes all of the functions of a cylinder head with two or more reciprocating cylinder head valves.
Prior art in the conversion of reciprocating engine thrust to rotary motion deals with various types of sinusoidal cams, which will be listed below. The sinusoidal cam, as first perfected in the Hermann engine, now known as the "Dynacam Engine" was certified by the Civil Aeronautics Administration for aircraft and helicopter use in 1953. The development of this engine was financed by the U.S. Government during WW-2. Most of the prior art since 1957 deals with varying applications of this engine's sinusoidal cam, which provides up to three times the torque of a conventional crankshaft engine. U.S. Pat. No. 3,385,051 of May, 1968 precisely describes the original Hermann engine sinusoidal cam, yet with a piston roller bearing having cam rollers at the exterior of the pistons which was probably inoperative, creating more eccentric piston-wall friction than the certified U.S. engine.
U.S. Pat. No. 5,103,778 of April, 1992 shows the correct Hermann engine four-cycle sinusoidal cam on a central shaft of a barrel type engine. The cam rollers are at the center of the pistons precisely as used in the well advertised Hermann "Dynacam" engine. This Patent specifically claims a conical rotary valve at the head of the barrel engine cylinders which would have the same stealing leakage's as a large flat plate circular rotary "disc" valve.
This tripling of the torque of the Hermann engine over that of a crankshaft machine is due to the fact that the torque is first doubled by the effect of each revolution of the drive shaft encompassing all four strokes of the four cycle engine process. Crankshaft engines receive only one power stroke to two revolutions of the drive shaft. Another 100 percent improvement in the torque is due to the fact that the cam drive roller bearing surface is always at an equal distance from the drive shaft during all power, exhaust, intake, and compression strokes.
This was and still is revolutionary, however a large component of the power stroke and the compression stroke must be carried by the side thrust of the piston cam rollers against the approximate 45 degree angle of the sinusoidal cam.
The result is a 30 percent loss of available power stroke thrust of the cam-driven engine and a significant friction loss of the piston rings against the cylinder walls. However, this is a tremendous improvement over that of a crankshaft drive which has near zero torque at the top-dead-center mode of the power stroke explosion, and the resulting side thrust of the crankshaft at the maximum torque at half-piston travel is far greater than that of the sinusoidal cam driven engine.
For instance, a 210 horsepower Hermann engine develops some 600 ft. pounds of torque. Even with the crankshaft offset a few degrees, (to improve the top-dead-center dilemma), modern engines produce a little better than 6 percent more torque than horsepower.
The invention herein described thus has the potential of developing four to five times the torque of a conventional crankshaft engine, with a considerable increase in horsepower due to the virtual elimination of sliding friction between pistons and cylinder walls. This is made possible by the unique positioning of the upper and lower alternating rack and pinion gears, with a rocking arm action of the rack-drive-gears, precisely at the center of the piston travel within the cylinders. Further, the quadruple, translating crank arms smoothly reverse the direction of the reciprocating pistons to mesh precisely with the intersecting teeth of the axial-alternating pinion gear drive system. This precise machining process could have been accomplished years ago with conventional gear cutting lathes. Computer aided machinery will only speed up this manufacturing process.
In order to better illustrate the significance of the torque conversion efficiencies of the three reciprocating combustion engines discussed, approximate calculations of piston power stroke conversion to rotary motion, friction and heat losses and effective moment arms of the piston connecting rod to the three types of rotary conversion are show in Tables 1 and 2 below.
A conventional, non-offset crankshaft engine was analyzed for each 15 degrees of crankshaft rotation, with the connecting rod being equal to 1.25 times the stroke. Published efficiencies of new engines are rated at 34% of the BTU input.
Although the loss of connecting rod vectored thrust to the crankshaft was only 4 percent, the loss of effective moment arm was 46 percent. Since a 6 inch stroke engine must have a 3 inch radius crankshaft, the effective radius during 180 degrees rotation during the power stroke was only 1.62 inches. The resulting torque delivered to the crankshaft was 50.8 percent of that available by a gear driven engine as described by this invention. The cam driven engine will achieve 70.7 percent of the available torque due to the approximate 45 degree angle between the cam roller of the piston and the sinusoidal cam itself.
The geared reciprocating engine will, by theoretical comparison, develop 127.3 percent of the available torque die to the fact that the gear pitch diameter is 1.273 times the stroke of the engine, and zero "side" loads are eliminated. Thus the geared engine has a potential of developing far greater torque than the comparative engines studied, with the efficiency of the geared engine approaching that of very efficient electric motor.
TABLE 1 ______________________________________ ENGINE HORSEPOWER EFFICIENCY 4 CYCLE RECIPROCATING COMBUSTION ENGINES *PISTON TO DRIVE SHAFT EFFI- FRICTION HEAT ESTIMATED ENGINE CIENCY LOSS LOSS EFFICIENCY ______________________________________ CRANK- 51.00% 8.50% 8.50% 34.00% SHAFT CAM 70.70% 3.50% 7.00% 60.20% DRIVEN GEAR 100.00% 2.00% 6.00% 92.00% DRIVEN *Theoreti- (estimated) (es- cal tima- ted) ______________________________________ *Note: 1953 Certificated cam aircraft engine developed 210 Horsepower and 600 ft. pounds max. torque: Torque/HP = 600/210 = 2.86 vs. 2.89 calculated
TABLE 2 ______________________________________ ENGINE TORQUE EFFICIENCY 4 CYCLE RECIPROCATING COMBUSTION ENGINES POWER STROKE TORQUE PER 720 PISTON CON- DEG. FORCE X VERSION Relative ROTA- MOM. EFFI- torque TION ARM CIENCY efficiency ENGINE (RPM) (relative) (less frict) factors ______________________________________ CRANK- 1.00 0.490 0.490 1.00 SHAFT CAM 2.00 0.707 1.414 2.89 DRIVEN* GEAR 2.00 1.273 2.546 5.20 DRIVEN (calculated) ______________________________________ *Note: 1953 Certificated cam aircraft engine developed 210 Horsepower and 600 ft. pounds max. torque: Torque/HP = 600/210 = 2.86 vs. 2.89 calculated
Rotary valves are very desirable in reducing the multiplicity of valves, valve seats, springs, rocker arms with cams and camshafts, comprising many pieces per cylinder head to only one basic operating part, per cylinder.
The spherical rotary valve consists of basically one moving part, and solves the inherent problem associated with large flat, conical, unsealed rotary disc valves previously attempted. It is well known that flat, circular rotary valves work well in small model aircraft and motorbike engines due to the fact that the bypass losses are not critical in small bore engines.
The use of a perfectly machined sphere rotating in a lower base of concentric circular (piston-type) rings is comparable to the perfected use of piston rings now employed in all cylinders of modern reciprocating engines. However, in the spherical rotary valve, the sealing rings are not subject to the incredible reciprocating action of the piston of the cylinder. The sphere always rotates in the same direction and at the same rotational speed, considerably reducing the wear on the sealing rings.
The opening of the sphere, with a specially curved interior baffle, is located just above the top of the sealing rings, and is supported by a unique "donut" type of cylinder head ring. This feature solves the critical sealing dilemma associated with un-sealed, sliding-surface rotary valves.
The resulting flow of exhaust and intake gases is improved substantially over that of the typical plunger type of reciprocating mushroom cylinder valve. In the spherical rotary valve, the interior three dimensionally curved baffle directs the intake and exhaust gases to form a very smooth laminar flow turn as opposed to the multiple reversal of the highly turbulent flow required in and around the geometry of a mushroom shaped valve.
Improvements in exhaust gas scavagening with the addition of supercharged inlet ports will reduce emission of undesirable combustion products that are of an environmental concern, as well as increasing the fuel efficiency of the engine.
The use of modern fuel injection will allow the supercharged inlet air to scavenge burnt exhaust gases on the intake stroke without loss of fuel.